Determination of Oxalic Acid in Urine Using an Electrochemical Alloy£­Dealloying Prepared Platinum Nanoparticles Modified Electrode

KeyWord:electrochemical alloy£­dealloying  platinum nanoparticles  modified electrode  oxalic acid£¨OA£©

Abstract:

      A platinum nanoparticles modified glassy carbon electrode£¨Pt NPs/GCE£© was fabricated by electrochemical alloy-dealloying method for the determination of oxalic acid£¨OA£© in urine£®The Pt£­Bi alloy particles were electrochemically deposited on the electrode surface at -0.4 V in HClO4 solution containing Bi£¨NO3£©3£¬K2PtCl4 and EDTA£®Then Bi was electrochemically dissolved from the alloy at 1.2 V in HClO4£¬and Pt NPs/GCE was obtained. The composition and morphology of the modifier on the electrode surface were characterized by SEM and EDS techniques£®Moreover£¬the electrochemical behavior of OA on this electrode was studied carefully based on the investigation of preparation conditions of the electrode£®The results showed that the electrochemical behavior of OA on this electrode was a diffusion-controlled irreversible oxidation process£®Benefiting from porous Pt NPs after electrochemical dealloying£¬this electrode had a larger active area£¬and thus had a high electrocatalytic activity for the oxidation of OA£®The results of optimizing the electrode preparation showed that the modified electrode exhibited an excellent analytical performance for OA when the deposition solution was 1.0 mmol/L K2PtCl6 + 3.0 mmol/L Bi£¨NO3£©3 + 3.0 mmol/L EDTA + 0.10 mol/L HClO4£¬the electrochemical alloy time was 500 s£¨-0.4 V£©£¬and the dealloying time was 1 000 s£¨1.2 V£©£®The linear ranges of amperometry determination for OA at 1.05 V in 0.10 mol/L HClO4 were 2.0 ¡Á 10-7£­4.9 ¡Á 10-4 mol/L and 4.9 ¡Á 10-4£­6.3 ¡Á 10-3 mol/L£¬with correlation coefficients£¨r2£© of 0.999 1 and 0.998 2£¬respectively£®The detection limit and sensitivity of the method for OA were 2.7 ¡Á 10-8 mol/L£¨3sb£© and 83 ¦ÌA/£¨mmol¡¤L-1£©£¬respectively£®Compared with other electrochemical sensors£¬this electrode had the characteristics of high sensitivity£¬wide linear range£¬as well as simple preparation£®The electrode was applied to the determination of OA in urine with spiked recoveries of 94.6%£­102% and RSDs of 2.2%£­4.7%.